Statistics

Author

Xiao, Keke

Chen, Yun

Jiang, Xie

Tyagi, Vinay Kumar

Zhou, Yan

Date of Issue

2016

School

School of Civil and Environmental Engineering

Research Centre

Nanyang Environment and Water Research Institute

Abstract

This study investigated the mechanism and effects of ultrasonic pretreatment followed by acidification on sludge dewaterability through looking at the changes of extracellular polymeric substances (EPS) content, composition and stratification. The results suggested sludge filterability was closely correlated with quantity of protein (R = 0.94, p < 0.01) and polysaccharide (R = 0.97, p < 0.01) present in loosely bound EPS rather than in soluble and tightly bound EPS. The fractions of polymers, especially tryptophan-like proteins and microbial by-product like material at molecular weight of 106–5 × 107 Da, were the key compounds related to sludge filterability. Ultrasonication may increase biopolymers concentrations that in turn deteriorate sludge filterability as evidenced at high ultrasonic power conditions. However, the subsequent acidification can reduce the concentrations of these organic compounds, reduce negative zeta potential, and increase floc size, thus increase sludge filterability. Combined ultrasonic-acid pretreamtent was more effective than the acidification treatment alone in reducing the concentrations of macromolecular compounds that may deteriorate sludge filterability.